Air heater



July 8, 1930. J. KEMNAL l AIR HEATER Filed Feb. 29, 1924 2 Sheets-Sheet l ORNEYS INVENTOR www J. KEMNAL .July s, 1930.

AIR HEATER Find Feb. 29. 1924 .x

2 Sheets-Sheet 2 IIIIIIIIIIIIIII' INVENTOR ATTORNEYS Patented July y8, 1930 UNITED STATES PATENT OFFICE JAMES KEMNAL, OF CHISLEHURST, ENGLAND, ASSIGNOR TO THE BABCOCK & WILCOX COMPANY, F BAYONNE, NEW JERSEY, A CORPORATION 0F NEW JERSEY i AIR HEATER Application filed. February 29, 1924. Serial N0. 696,098.

My invention relates to air heaters of the type in which furnace gases and the like are caused to give up a portion of their heat by passing through tubes over which the air to '5 be heated is passed, and will be best understood by reference to the following description and annexed drawings, in which Fig. 1 is a view -in vertical section of an illustrative embodiment of my invention; Fig. 2 is an enlarged view, partly in section, of the tube tops with the top tube sheet removed; Fig. 3 is a plan view of elements shown in Flg. 2; Flg.

4 is an enlarged view partly in section of the bottom end of a tube Fig. 5 is a similar view of the upper portion thereof, a part of the tube being broken away; and Fig. 6 is a view of a spiral strip which in the embodiment shown is suspended in each of the tubes.

In the illustrative embodiment shown, 10

denotes a casing having an inlet opening 11 and an exit opening 12 for the air to be heated. Atop tube sheet 13 andabottom tubesleet 14 are bolted to casing 10 and serve to hold in place tubes 15, which as indicated in Fig. 1, are preferably suspended from tube sheet 13 by expanding the upper ends 15a of the tubes tightly into plate 13, and swelling the lower' ends to fit slidingly in plate 14. This arrangement is of considerable importance in 3o view of the fact that some of the tubes may be heated to a greater extent than others, particularly when they are cleaned with a steam blower or lance, and unless such a provision was made undue strain in the apparatus would be set up.

The casing at the lower end communicates with a conduit 16 by means of an adapting portion 17 through which the furnace or otherheating gases are conducted from the heater, said' gases entering the tubes at the top which, when the heater is in use, is connected with a conduit (not shown) leading from the furnace or other source of hot gases. Battles 18 and 19 serve to direct the air back and forth across the exterior of the tubes 15.

In each of the tubes 15 I provide a strip 20 ofq suitable material of a width approximately equal to the internal diameter of the tubes and preferably of spiral form as shown. These strips 20 extend the full length of the 23 on the ends of cross-piece 21. By means of this arrangement a number of strips 20 may be simultaneously removed from the tubes 15 whenever this is necessary for cleaning or for any other purpose.

When the air heater is in use without the v strips of my invention, it will be found that a deposit of dust and soot collects inside the tubes, particularly toward the lower ends thereof. This deposit greatly diminishes the etciency of the heater. By the use of the v strips 20, however, I have found that this deposit is minimized to a very substantial degree. The strips equalize the flow of the gases between the tubes and increase the velocity of thegases passing through the tubes, particularly those portions of them close to the walls of the tubes, whereby less time is afforded for the deposition of solid particles from the gases upon the contacting walls.

Moreover, by making the strips movable any deposit which collects in the tubes and on the strips may be readily removed by moving the strips up and down so as to scrape the inside of the tubes and jarring the strips to shake the deposit therefrom. The strips can be entirely removed if so desired and all of the surface cleaned.

Furthermore, by arranging the heater so that the gases flow in a downward direction the tendency of the soot and cinder carried by the gases to stick on the interior of the tubes is reduced. By employing the strips of spiral form inside of the tubes the larger particles of cinder are thrown voutward by centrifugal force against the inside of the tubes and serve to remove any of the finer particles which have become lodged on the surface of the tubes.

While I have obtained excellent results using the strips in the form of a spiral, it will be understood that the use of various other means for subdividing the gas streams in the tubes will to some degree accomplish the results Which I obtain. It vvill be understood therefore that other forms of strips may be used without departing from the spirit of my invention.

I claim:

l. In an air heater, a casing having an air inlet and an air outlet, tube sheets in said casing, tubes for the heating gases passing through said tube sheets, strips in said tubes Vof a Width approximately the internal diameter of the tubes, and rigid cross-pieces each connecting a plurality of projecting ends ofsaid strips, by means of Which cross-pieces said strips may be reciprocated, the other ends of said strips being unconnected to each other, and means for causing relatively hot gases carrying solid particles in suspension to flow through said tubes.

2. In an air heater, a casing having an air inlet and an air outlet` tube sheets in said casing, tubes for the heating gases passing through said tube sheets, spiral strips in said tubes of a Width approximately the internal diameter of the tubes, and rigid cross-pieces each connecting a plurality of projecting ends of said strips, by means of which cross-pieces said strips may be reciprocated, the other ends of said strips being unconnected to each other, and means for causing relatively hot gases carrying solid particles in suspension to flow through said tubes.

3. 4In an air heater, a casing having an air inlet and an air outlet, tube sheets in said casing, vertical tubes for the heating gases passing through said tube sheets, spiral strips in said tubes of a Width approximately the internal diameter of the tubes and rigid crosspieces each connecting a plurality. of projecting ends of said strips, by means of which cross-pieces said strips may be reciprocated, the other ends of said strips being unconnected to each other, said cross-pieces resting upon the tube ends and serving to suspend said strips in said tubes and means for causing relatively hot gases carrying solid particles in suspension to iow through said tubes.

4. In a device for transferring heat from a relatively hot gas carrying solid particles to a relatively cool gas, a casing, tube sheets extending across said casing, vertically extending tubes secured to the upper tube sheet and slidable in openings in the lower tube sheet, means for causing the relatively hot gases to enter the ends of said tubes and to ow through said tubes, and means for passing gas over said tubes.

5. In an air heater, a casing having an air inlet and an air outlet, tube sheets in said casing, tubes for the heating gases passing through said tube sheets, the gas inlet ends of the tubes adjacent one of said tube sheets being expanded thereinto, the other ends of said tubes passing through holes in said other other tube sheet.

JAMES KEMNAL. 

